Photocatalytic degradation of ketoconazole by Z-scheme Ag3PO4/graphene oxide: response surface modeling and optimization

Coprecipitation aided synthesis of bimetallic silver tungstate: a response surface simulation of sunlight-driven photocatalytic removal of 2,4-dichlorophenol

In the present study, the response surface methodology (RSM) model was used to investigate the photocatalytic performance of silver tungstate (Ag₂WO₄) in the removal of 2,4-dichlorophenol (2,4-DCP) under natural sunlight. The Ag₂WO₄ which has nanoflower-like structure was synthesized by a coprecipitation method. The synthesized photocatalyst was characterized for FESEM, TEM, EDX, XRD, FTIR, and UV-Vis spectroscopy. RSM was employed to scrutinize the suitable model to yield a profound pollutant removal rate. The four independent factors such as pollutant concentration, catalyst dosage, pH, and contact time are simulated using RSM. A total of 91% of 2,4-DCP degradation was achieved at a higher catalyst dosage and lower pollutant concentration with a contact duration of 8 h in an alkaline pH condition. The coefficient of regression (R²) and probability value (P) were 0.98 and 0.0472, respectively, which confirmed the ideality of RSM modeling. The study discusses on the possible photocatalytic degradation mechanisms of 2,4-DCP. The results showed a significant dependence of the photocatalytic removal of 2,4-DCP on the functional parameters.

Graphene-based photocatalytic nanocomposites used to treat pharmaceutical and personal care product wastewater: A review

Photocatalytic technology has been widely studied by researchers in the field of environmental purification. This technology can not only completely convert organic pollutants into small molecules of CO₂ and H₂O through redox reactions but also remove metal ions and other inorganic substances from water. This article reviews the research progress of graphene-based photocatalytic nanocomposites in the treatment of wastewater. First, we elucidate the basic principles of photocatalysis, the types of graphene-based nanocomposites, and the role of graphene in photocatalysis (e.g., graphene can accelerate the separation of photon-hole pairs and increase the intensity and range of light absorption). Second, the preparation, characterization, and application of composites in wastewater are introduced. We also discuss the kinetic model of the photocatalytic degradation of pollutants. Finally, the enhancement mechanism of graphene in terms of photocatalysis is not completely clear, and graphene-based photocatalysts with high catalytic efficiency, low cost, and large-scale production have not yet appeared, so there is an urgent need for more extensive and in-depth research.

Graphene-Based Composites as Catalysts for the Degradation of Pharmaceuticals

The incessant release of pharmaceuticals into the aquatic environment continues to be a subject of increasing concern. This is because of the growing demand for potable water sources and the potential health hazards which these pollutants pose to aquatic animals and humans. The inability of conventional water treatment systems to remove these compounds creates the need for new treatment systems in order to deal with these class of compounds. This review focuses on advanced oxidation processes that employ graphene-based composites as catalysts for the degradation of pharmaceuticals. These composites have been identified to possess enhanced catalytic activity due to increased surface area and reduced charge carrier recombination. The techniques employed in synthesizing these composites have been explored and five different advanced oxidation processes-direct degradation process, chemical oxidation process, photocatalysis, electrocatalyis processes and sonocatalytic/sono-photocatalytic processes-have been studied in terms of their enhanced catalytic activity. Finally, a comparative analysis of the processes that employ graphene-based composites was done in terms of process efficiency, reaction rate, mineralization efficiency and time required to achieve 90% degradation.

Graphitic carbon nitride: a sustainable photocatalyst for organic pollutant degradation and antibacterial applications

Recently, graphitic carbon nitride (GCN) has been found to be of great interest in various sustainable applications. In this study, a simple preparation method using urea was utilized to synthesize GCN. In order to understand various morphological, structural, and optical aspects of the as-prepared sample, GCN was characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Brunauere-Emmette-Teller (BET), scanning electron microscopy (SEM), and diffused reflectance spectra (DRS) analysis. The visible-light-driven photocatalytic activity of prepared GCN was analyzed for various cationic dyes (Crystal violet, rose bengal, rhodamine B, auramine O, methylene blue) and anionic dyes (phenol red, xylenol orange, cresol red, methyl orange). The calculated efficiencies of degradation and values of apparent rate constant for all dye samples suggested that cationic dyes are more actively degraded using GCN than anionic dyes. In addition, GCN was further analyzed for its splendid antibacterial activity against pathogenic bacteria (Klebsiella pneumonia and Escherichia coli). The synthesized photocatalyst holds a bright scope for the efficient remediation of organic pollutants and bacterial disinfection in wastewater. Graphical abstract.